Method of forming knives.



E. L. HURD.

METHOD OF FORMING KNIVES.

APPLICATION FILED JULY 30, 1912 1,090,153, Patented Mar. 17, 1914.

,w wmmm Unit i. TAT% PATN FFXCE,

EDWARD L. HURD, OF MILTON, MASSACHUSETTS, ASSIGNOR T0 UNITED SHOE MACHINERY COMPANY, OF PATERSON. NEW JERSEY, A CORPORATION OF NEW JERSEY.

METHOD OF FORMING KNIVES.

Specification of Letters Patent.

Patented Mar. 17, 1914.

To all whom it may concern Be it known that I, EDWARD L. Horn), a citizen of the United States, residing at Nib ton, in the county of Norfolk and State of Massachusetts, have invented certain Improvements in Methods of Forming Knives, of which the following description in connection with the accompanying drawings, is a specification. like reference characters on the drawings indicating like parts in the several figures.

This invention relates to methods of making knives, especially knives for use in the manufacture of shoes and particularly knives for brcasting the heels of boots and shoes.

It is usual, in the manufacture of shoes, to remove the forward portion of the heel by means of a knife of chisel form which is caused to move in a direction approximately perpendicular to the tread face of the heel. The knife is usually gouge-shaped or transversely convex toward the heel for the purpose of giving the heel breast a concave sur face. In the manufacture of knives for this purpose, the lower cutting portion is given a cutting temper while the shank or port on which is secured in the machine has a sprlng temper to prevent breakage. I have found that these breasting knife blanks are caused, in the process of ten'ipering'. to bulge at the back so that the rear face of the knife bows outwardly, whereas, for the best results, a heel breasting knife should bow slightly inwardly in order to cause its lower cutting edge portion to flare outwardly a trifle to give clearance for facilitating the heel breasting cut. This shape has been given to knives prior to this invention by grinding the blanks to remove the bulge but that method is comparatively slow and expensive.

It is the object of the present invention to provide an economical method of making, for heel lei-casting or analogous purposes, knives which will have the described flaring shape without a great amount of grinding.

It is a characteristic of the present invention that provision is made, in the process of initially forming the knife to utilize the described distortion, which takes place in tenipering, to perfect the shape of the knife; that is, the knife is first so shaped that when it is tempered it will assume, as nearly as may be, the desired final contour. "tore specifically knives are hot pressed from a plate of steel between dies which are so designed that the knife instead of being truly cylindrical when it emerges from the dies is deformed or misshapen to a predetermined extent. so that when it is tempered itwill. by reason of the contraction incident to the tempering process, assume a shape which is substantially that desired in the finished knife and only a slight amount of grinding is necessary to finish it. i i

[n the application of the invention to the ftn'mation of knives for the purpose described the blank, when it emerges from the dies. has a slight flare outwardly from its -onvex surface, the flared edge portion having pproxiniatcly a conical surface. \Vhen a knife so shaped is subjected to the tempering operation. the stresses, which in the knife of ordinary manufacture. cause it to bulge at the back, will, in the knife as formed in accordance with my invention, cause the flare to be diminished so that when ground to finish it will assume a more nearly cylindrical form. with only sullicient clearance to facilitate the action of the knife and moreover t1 3 amount of grinding required to finish the knife will be very small.

Figure L shows in section and perspective a knife blank struck from a bar of steel. Fig. 2 shows in section and perspective the same blank after it has been heated and subjected to a forming operation between dies so formed as to give the knife :1 double curvature. resulting in a rearward flare at the end which is to become the edge of the knife; Fig. 3 shows in section and perspective the blank after it has been subjected to the tempering operation; Fig. 4 shows in section and perspective the finished knife, the position of the shoe heel being shown in dotted lines in connection with the sectional view.

In the manufacture of knives by my improved metbod, the knife blank as illustratcd in Fig. 1 is first struck from a flat. bar of steel having the width of the knife at its widest portion. The blank thus formed is heated and hot pressed between dies so formed as to give it the configuration illustrated in Fig. 2. The blank thus formed has the usual gouge shape or substantially cylindrical curvature for giving the face of the breast a concave form and has also a slight longitudinal curvature about a locus at the rear or on the convex side of the knife. This locus is preferably only slightly above the cutting edge and results in giving the lower or cutting portion of the knife a flare rearwardly or toward the position of the heel being breasted. This flare is, of course, very slight, amounting in practice to from l/6 l to 1/32 of an inch. The blank is next subjected to the tempering operation from which itemerges in the form illustrated in Fig. 3. T have found in practice that the stresses set up incident to the tempering operation tend to draw these blanks back to a truly cylindrical. form, the rearward flare being preferably very nearly obliterated. This change of form by the tempering operation is probably due, partially at least, to the form of the knife. The knife is finished by grinding the edge and finishing off the back of the knife which preferably will retain a slight remnant of the flare pressed into it by the dies to afford .a clearance for the knife edge during the breasting cut. In Fig. 4c the knife is shown as having a slight clearance which is rendered more apparent by finishing olf the scale formed on the back of the knife by the tempering operation. In knives as usually made for this purpose there is considerable bulge at the back due to distortion in tempering and considerable grinding is necessary to reduce them even to a substantially cylindrical form. Knives made by my improved method have sufficient clearance to avoid friction of the back of the knife against the heel with the attendant disadvantages above enumerated.

Knives made in accordance with this invention make a smooth clean out without the stepped breast, and moreover work very quietly without any of the groaning which is usual with knives of the usual construction.

Having described my invention, what I claim as new and desire to secure by Letters Patent of the United States is 1. That improvement in methods of manufacturing gouge-shaped knives for use in brcasting heels which consists informing a blank from a sheet of steel which has a flat shank portion, a substantially cylindrical blade portion, and a flared edgeportion; and then tempering the knife whereby the flare is reduced to approximate conformity with the cylindrical portion.

That improvement in methods of manufacturing knives which consists in forming a blank the general shape of which is substantially a portion of a cylinder and which has a. flare at the edge on the convex face thereof, and then tempering a portion of the blank including the flared portion whereby the flare is reduced and the knife is caused to assume a more nearly cylindrical form.

3. That improvement in methods of manufacturing knives which consists in forming a blank which is curved in a plane parallel to its cutting edge, portions of the blank bei ng deformed in a manner such that the def ormation will be reduced by the tempering process, then tempering a portion, or all, of the blank including the deformed portion whereby the deformation is reduced and the knife is caused to assume more nearly the desired shape, and then finishing the knife by grinding.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

EDXVARD L. HURD.

Vi itnesses Anson B. Vnnowoon, VVILLIAM ]3 KING.

Copies of this trade-mark may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. i 

